Technical Knock sound after release the clutch at startup

[electric73]

My car is Bravo t-get 2007. Every time when starts the engine, I'm pressing the clutch. Sometimes, on the cold starts, a knock sound appears just after releasing the clutch. In driving everything is normal. Do you experience the same and what could be the reason?

 

[bugsymike]

My car is Bravo t-get 2007. Every time when starts the engine, I'm pressing the clutch. Sometimes, on the cold starts, a knock sound appears just after releasing the clutch. In driving everything is normal. Do you experience the same and what could be the reason?

If you get the same noise in first gear with foot off clutch, but if you go on and off the accelerator in a jerky fashion, then a common fault is the "dog bone" bottom gearbox mount.
It may look something like this, which is a common cause of a knock.

 

[electric73]

i don't have such symptoms. Thought that the clutch may got sticky after a longer staying but not sure if that's possible

 

[bugsymike]

i don't have such symptoms. Thought that the clutch may got sticky after a longer staying but not sure if that's possible

Some Fiats experience a "lazy" clutch pedal, slow to return , possibly due to a sticking master cylinder or other faulty clutch hydraulics.
There are several threads on Forum about this, if you feel that is likely.